During the construction of buildings, chimneys have been erected having flues of varying internal dimensions. Frequently, due to the material selected for the chimney, the age of the chimney, and/or the exposure of the chimney to adverse weather or use conditions, a necessity arises for the lining of a chimney with a masonry mortar compound. In the past, the chimney lining devices used during the application of masonry mortar compounds have not been adjustable in size for use with varying sized chimneys. Chimney lining devices as known generally were enlarged by the inclusion of expansion slats. The incorporation of expansion slats into a chimney lining device is a time consuming process. In addition, the inclusion of expandable members or slats significantly reduced the structural integrity of the device, especially when exposed to the vibrational forces required for compaction of a masonry mortar compound to the interior walls of the chimney. As such, an expandable chimney lining device frequently fractured, bent or failed following prolonged use. In the past, the cleaning and removal of expansion members or slats from a chimney lining device was difficult and time consuming. The present invention eliminates these described problems while simultaneously enhancing the structural strength, durability, and useful life of a chimney lining device.